Olefin-based thermoplastic elastomers are lightweight and easy to recycle, and hence are widely used for automobile parts, industrial machine parts, electronic and electrical parts, construction materials, and the like, as thermoplastic elastomers of an energy saving and resources saving type, particularly as substitutes for vulcanized rubbers.
However, conventional olefin-based thermoplastic elastomers have the disadvantage of being inferior in tensile strength, fracture elongation, and compression set, compared to vulcanized rubbers, and improvement therein has been strongly demanded.
As an olefin-based thermoplastic elastomer improved in these characteristics, a thermoplastic elastomer obtained by dynamically cross-linking a crystalline polyolefin resin and an ethylene.propylene.non-conjugated polyene copolymer rubber under specific conditions is proposed in Patent Document 1.
In some applications (for example, automobile parts applications), a thermoplastic elastomer that is positively not cross-linked and obtained by only dynamic thermal treatment (dynamic kneading) may also be used (see Patent Document 2).